Method and apparatus for coring wells



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Ralph L-Hendrzkkson INVENTOR.

' ATTORWY Feb. 12, 1952 R. L. HENDRICKSON METHOD AND APPARATUS FOR CORING WELLS Filed June 26, 1947 1952 R. L. HENDRICKSON 2,585,386

METHOD AND APPARATUS FOR CORING WELLS Filed June 26, 1947 3 Sheets-Sheet 2 IN VEN TOR.

A T TORNE Y Ra i 212,1; .Hendnkk/on I Feb. 12, 1952 R. L. HENDRICKSON METHOD AND APPARATUS FOR CORING WELLS 3 Sheets-Sheet 5 Filed June 26, 1947 F Us I ATTORNEY Patented Feb. 12, 1952 UNITED "STATES PATENT OFFICE Ralph-L. 'Hendrickson, Hobbs, N. Mex., assignor to Stanolind Oil and Gas Company, Tulsa, kla.,.a corporation of Delaware Application June'26, 1947, Serial No.'757,266

14 Claims. 1

This invention pertains generally'to sampling sub-surface formations by coring. Morepartic- .ularly, it deals with an improvement in the art of samplingformations at the bottom ofa hole by employing reverse-circulation drilling to cut the core and circulate it to the surface ina'core barrel.

As used herein fdirect circulation :refers'to circulation of the drilling fluid downwardly in the drill pipe in a drilling well and upwardly in the well outside the drill "pipe. Direct-circulation drilling is defined as drilling which is carried on while the fluid is in direct circulation. Conversely, reverse circulation as used herein refers to circulation of drilling fluid upwardly in the drill pipe in a drilling well and downwardly in the well outside the drill pipe. Reverse-circulation drilling is therefore drilling which is carried on while the fluid is in reverse circulation.

In the art of sampling deep subterranean formations by circulating cores to the surface in the drilling fluid, two general methods have been practiced. In one a core barrel is employed adjacent the bit, and in the otherthe core fragments are transmitted to the surface through the drill pipe directly as the cores are cut and broken oil.

In the former method a core barrel is pum ed to the bottom by direct circulation and held in position contiguous to the drill bit, as'a general rule by the pressure of the drilling fluid, while the core is cut and deposited in the barrel. Constricted ports are provided around the core barrel which by the pressure drop of the fluid tend to hold the barrel in position at the bit where it receives the cores as they are out. When the barrel is full of cuttings or cores, reverse circulation is employed to transmit the barrel containing the cutt ngs or cores to the surface in the drilling 'fiuid. This method of coring has many advantages over previous methods of coring in which all of the drillpipe had to be retracted in order to recover the core. However, many of the limitations of the earlier practices are retained in this method. For examplathe washing action of the drilling fluid which tends to dissipate thecore'also tends toprevent the core particles from entering the-barrel, due to the use of direct-circulation drilling, and 'accorclprovement uponthe;previouslydescribed method in that the recovery is increased bythetendenc'y core barrel.

of the crumbled core particles to be removed with the core. In the case of coring by'reverse circulation without a core barrel, I have found that many difiiculties are encountered in that the small core particles and cuttings tend to rise in the drill pipe at different rates, depending upon size and shape of the particles. There is a tendency for two particles or a fragment and afull-diameter core to pass in the drill pipe and to wedge therein and plug the drill pipe. Furthermore, such cores are invariably broken in random lengths, and certain lengths cannot be transmitted in the fluid through the drill pipe without also wedging and plugging the drill pipe and consequent loss of time, etc. In the case of coring by reverse circulation with a core barrel, many of the disadvantages of the previously described processes have been overcome. For example, the per cent core recovery issubstantially increased and the plugging of the drill pipe as previously described is completely avoided. Howeven'even in this improved process considerable drilling time is'lost in recovering the core barrel after the core-has been cut and deposited in the barrel. Prior to my invention it has been necessary to stop drilling and lower an unlatching mechanism to the barrel and then either lift the barrel or circulate the barrel to the surface.

It is, therefore, an object of this invention to provide an improved method for coring a subterranean formation. Another object of this invention is to provide a method of coring'subterranean formations wherein a core barrel is employed during reverse-circulation drilling,'and wherein such core barrel and core are removed from the drill pipe by reverse-circulation drilling. It is another object to provide an improved coring device which can be circulated down the drill pipe and latched in position adjacent the drill bit to take'a sample of the formation during'reverse-circulation drilling, and, after taking such sample, which can be released without discontinuing drilling operations and lowering a tool into the drill pipe to release and/ or lift the It is another object of this invention to provide a latching and releasing means "for holding a core barrel in position adjacent the bit of a drilling device, the latching and re- .Figure 1 isua view with a. fragmentary central longitudinal 'sectionthrough the lower portion of a drill stem equipped'with and showing a form ,of'apparatus used in-myinvention;

Figure 2 is a transverse section on the plane 2-2 of Figure 1 showing certain operational fea-- tures of one embodiment apparatus employed in my invention;

Figure 3 is a view partly in section and Figure 4 is a sectional view of apparatus according to my invention, employing alternative principles for latching the core barrel adjacent the bit and releasing the core barrel; and

Figure 5 is a fragmentary longitudinal section taken on plane 55 of Figure 4 showing certain operational features of that apparatus.

By this invention the previously described processes or methods have been improved by employing reverse-circulation drilling, not only to cut the core and deposit it in the barrel, but also to circulate the core to the surface in a barrel without substantial loss of drilling time. Improved apparatus is also provided to release the core barrel remotely when a desired amount of core has been cut. Inasmuch as drilling may proceed during the time the core is being removed, considerable drilling time as well as the cores are saved by this invention.

Referring now to Figure 1, the lower end of a drill pipe I is illustrated to show generally the location of the novel apparatus employed in the operation of this invention. The remainder of the drill pipe, including a core catcher at the surface, can be standard equipment such as shown in U. S. Patent 2,135,737 Stokes, and so for clarity is not shown or described here. A drillpipe enlargement H is provided at the lower end of drill pipe ID providing a fluid passage l2 between core barrel I3 and the enlargement H. As explained in greater detail hereinafter, this passage provides means for fluid to bypass the core barrel during the time that a core is being cut and deposited in the core barrel It. This core barrel |3 has an external diameter nearly equal to the internal diameter of drill pipe l0, whereby fluid circulation in the drill pipe tends to move the core barrel by piston action. Sealing means such as rubber ring l4, cups, or the like, however, may be attached to the core barrel 53 to provide a better seal between the core barrel and the drill pipe, thus tending to produce a more positive piston action in the core barrel. A special collar is attached to the lower end of enlargement H. This collar preferably has an internal bore |6 which has substantially the same diameter as the external diameter of core barrel l3. The special collar is also provided with a fluid passage H, the function of which will be explained in greater detail hereafter. A latching device I8 is provided at'the lower end of the special collar 15. This latching device is adapted to hold core barrel l3 in position adjacent the bit while the core is being out even though the fluid is being circulated upwardly in the drill pipe. The latching device consists of a latch l9 which rotates on pin 2|. This pin in turn is anchored in the special collar [5 as shown more clearly in Figure 2. The latch is provided with a hook 22 which is adapted to engage the core barrel in a groove 23, thus holding the core barrel in position. The latch is actuated by a variable-diameter groove or cam 24 in the body of valve 25 as shown. When drill pipe I0 is turned rotated clockwise looking down from the surface whereby shoulder 26 on special collar l5 contacts the shoulder 21 on valve 25, latch I9 takes the position shown in groove 24. That is, the hook 22 engages groove 23 holding the core barrel IS in the position shown. Valve 25 is held in position adjacent special collar l5 by a sleeve 28 in such a manner that fluid passage 29 in the valve is in alignment with fluid passage i! of special collar l5. Special collar 15 and valve 25 are each provided with projections 3| 1 and 32, respectively, which prevent rotation except over a small angle 0, as shown in Figure 2. When projection 3| is moved by the clockwise rotation of the drill pipe, shoulder 26 engages shoulder 21 of the projection 32, tending to drive the bit, which is attached to the valve by threads 33. At the same time ports 29 and IT are brought into communication whereby fluid passes freely through the communicating ports.

When a sufilcient amount of core has been collected in core barrel |3, the core barrel is remotely released. As used in this specification and the appended claims remotely released means that the core barrel which is latched in position adjacent the bit to receive the core is unlatched or released by the action of the drill pipe or the core and specifically excludes the use of actuating means inserted into the drill pipe and lowered to the core barrel to release any latching means employed for holding the core barrel adjacent the bit during reverse-circulation drilling. The drill pipe is rotated counterclockwise, bringing shoulder 34 of projection 3| into contact with shoulder 35 of projection 32. That is, there is relative rotation between the drill pipe and the bit through an angle 0, which at the same time rotates port 29 with respect to port through an angle 0 as shown in Figure 2, thereby closing this fluid passage. By this same relative rotation latch I9 is moved by cam 24 disconnecting hook 22 from groove 23 and releasing core barrel |3. Inasmuch as reversecirculation drilling is employed to cut the core, the fluid movement in the drill pipe It now tends to raise the core barrel in drill pipe in. Means are, as stated above, provided at the surface for catching this core barrel and unloading same. Drilling may obviously proceed as usual even though the core barrel has been removed. When the core has been removed from core barrel IS, the barrel may again be inserted into the drill pipe H1 and pumped into position at or adjacent the bit by circulating fluid down the drill pipe, i. e., by direct circulation. When the core barrel is in position, the drill pipe may again be rotated in reverse temporarily and then turned clockwise to move upper special drill collar |5 with respect to valve-25 and latch core barrel l3 into position as shown. While I have shown in this embodiment only one fluid passage comprising ports 29 and IT, it is obvious that two or more such fluid passages could be provided and also that twoor more latching devices could be provided. I have found also that a core catcher 36 may be employed to some advantage in some cases.

The embodiment of this invention as shown in Figure 3, like that embodiment shown-in Figure 1, is directed to a device for holding a core barrel in position adjacent a bit during the time that a core is being cut by reverse circulation. Means are also provided for remotely releasing the core barrel, thus saving valuable drilling time. In this embodiment the core barrel is held in position merely bythe weight on the drill pipe H]. At the lower end of the drill pipe a spline 40 between mandrel. 4| and sleeve 42 permits longitudinal motion of the drill pipe. ll] relative to the sleeve 42 and the bit without permittinglrotation there between. A shoulder 43 on mandrel 4| is adapt ed to engage the projecting grooves 44 .of spline 4U tolift the-bit, etc. One or more flexible spring catches 45am connected to the mandrel 4l for the purposeof holding core barrel l3-down against the upward force of the drilling fluid.

In operation, thecorebarrel I3 is introduced intothe-drill pipe I lI-atthe surfaceand pumped by 'directcirculation through the drill pipe into theposition shown. Before drilling is commenced and thecirculation of the fluid is reversed, however, the drill pipe is lowered until the bit strikes the bottom of the hole. As the weight of the drill pipe is applied to the bit which is connected'to collar 4?, spring catches 45 are deflected radially inward by the inclined surface 48, thus latching in groove 23 of core barrel I3 33 shown in invisible outline. Inasmuch as the weight is'maintained -on the 'drill pipe during drilling, a core barrel is held in position by these spring'catches 45 until it-is desired to release the core barrel. At this time the drill pipe l0 is raised;slightly-to extend thisflatching mechanism and withdraw springs 45 from the groove23-and to release the core barrel, which may then be circulated to-thesurface :in the drilling fluid. [Turning now to the description of a third embodiment of apparatus which maybe employed in this invention, I have shown in Figures 4 and 5 means adapted to latch and unlatch-remotely a corebarrel-"in position adjacent a bit. In this embodiment, .howeventhe core barrel is latched in position automatically and unlatched by the action of the core after apredetermined amount of core has'been cut and circulated into the core barrel. More specifically, in this apparatus the drill pipe I0 is screwed into a collar 5! having fluid passages or grooves 54. This collar includes at its lojwerpenda shoulder 52, which not only provides meansfor'latching the barrel in position but also produces a restricted fluid passage 53. This restricted fluid passage, as described more fully hereinafter, producesa pressure drop in the drilling'jflu'id sufficient to lift core barrel i3 when the barrel isunlatchedand the fluidis circulated upwardly in. the drill pipe. A drillbit E'Imay be attached-to the lower end of drill collar .55 according to usual practice.

.The latchingdevices in this caseare associated .withthe core barrel [3 and consist of two or more latches .58 which are adapted to seat on shoulder 52 .to .hold the ,core barrel in position. These latches are rotatably mounted on a pin 5,9 whichis anchored into the-core barrel head .60. Thelatches are urged' outwardly by springs orby the weight of triggertl through pinBZ, .which operatesin the cams 63 of the latches. A force on the. bottom shoe 54 oftrigger 6| tends to raise the trigger, contractthe latches, and permit the core barrel to ,move upwardly. Trigger 6! may be raised'by either a core strikingthe shoe GLor-by-a fishing device which may latch on fishing spear 65. This fishing spear is provided. however, for useonly-inan-emergency and is not generally employed to unlatch the core barrel.

inasmuch as drilling would necessarily have to be discontinued during the time the latching and unlatching device-is in the drill pipe. A perforation .BBthrough the core barrel head 6!] provides means for "displacing fluid inxthe barrel ahead of the core-rand equalizes thepressure-onboth :sides-of the head whereby the trigger will not be releasedprematurely by flu-idpressure. In this embodiment core drilling may proceed using reverse circulation of the fluid until the top of the core strikes shoe 64. At this time the trigger BI is :raised, contracting latches 5B.-and permitting the .core barrel to riseibythe :fluid pressure drop through constricted-fluid:passagee53 into;the;drill pipe. This core barrel could alsoi'beraised into drill pipe In ;by :the force of the :cores. Under any circumstance, when the core barrel is .displaced into :the drill pipe, cups 1.6.1 or .-.other pack. ingmeans seal the annularspacebetween the drill pipe and the core barrel, causing the core'barrel to risein'the drillpipe in the-mannerof apiston to the surface. The core is thus automatically retrieved when the core barrel is'full of core, and no timeis lost in the drilling operationby lowering anunlatching means into the well.

It may be seen, therefore, that my invention maybe practiced with a number of devices embodying generally a core barrel which may he latched in position adjacent the bit to receive the cores during reverse-circulation drilling, :and means for remotely releasing the core "barrel without materially interrupting :drilling opera.- tions. The invention should therefore not he construed to be limited to the specific "devices disclosed, but only by the scope of the appended claims.

I claim:

1. The method of taking core samples of -for mations being penetrated by a bit including the steps of "flowing a core barrel by direct circulation to a position adjacent the "bit, releasably latching said core barreladjacentsaid bit, cutting a core and collecting said coreinsaid-core barrel while maintaining reverse-circulation drilling, releasing said core barrel and flowing said core barrel containing saidsamp1e=to the surface of the earth while continuing said reverse-circulation drilling.

2. In a method of takingcore samples during drilling operations, the improvement comprising circulating a core barrel to a point adjacent the drilling zone, releasably latching the core barrel in position'in the drill stem within the drilling zone, cutting a core sample while maintainingreverse-circulation drilling anddisplacing said'core sample into said core barrel 'by reverse circulation, remotely releasing said core barrel, and circulating said core barrel containing said core sample to themouth of the well.

3. A method of sampling formations penetrated by a drill bit comprising the steps of circulating a core barrelto a point adjacent to said drill bit by direct circulation, releasably anchoring said core barrel at said point, establishing reversecirculation drilling, takinga sample of said formation while conducting said reverse-circulation drilling, remotely releasing the core barrel containing said-sample while continuing the reversecirculation drilling, and flowing said corebarrel to thesurface by continuing said reverse circulation drilling.

"4.71m a method of sampling thesubterranean formations penetrated by a bit at the end of a drill stem wherein the sample'as'it is cut-is displaced into a core barrel, the improvement comprising maintaining said core barrel in position adjacent the bit during reverse-circulation drillingand remotely releasing saidcore barrel whereby saidgsample maybe delivered to the surface without materially.interfering with drilling operations- .5. A metbodo sa nplins,.tbeiformat ons.nen tr ted .bya bit at theme of a dr l stem ecniprising positioning a core barrel adjacent said bit, cutting a sample of said formation and displacing it into said core barrel by reverse-circulation' drilling, remotely releasing said core barrel containing said sample, and raising said core barrel through said drill stem by reverse circulation of the drilling fluid.

6. A method of sampling the formations penetrated by a bit at the end of a drill stem comprising passing a core barrel by direct circulation through said drill stem to a position adjacent said bit, maintaining said core barrel in said position, cutting a sample of said formation and displacing it into said core barrel by reversecirculation drilling, remotely releasing said core barrel containing said sample, and raising said core barrel through said drill stem by reverse circulation of the drilling fluid.

7. A method of sampling formations penetrated by a bit at the end of a drill stem comprising lowering a core barrel through said drill stem to a position adjacent said bit, rotating said drill stem in one direction to latch said core barrel in said position, cutting a sample of said formation and displacing it into said core barrel by reverse-circulation drilling, rotating said drill s'tem'in the opposite direction to release said core barrel containing said sample and raising same through said drill stem by reverse circulation of the drilling fluid.

8. A method of sampling subterranean formations penetrated by a bit at the end of a drill stem in the process of rotary drilling, comprising lowering a core barrel through said drill stem to a position adjacent said drill bit, cutting a sample of said formation and displacing it into said core barrel, releasing said. core barrel by raising said drill stem, and raising said core barrel through said drill stem by reverse circulation of the drilling fluid.

9. A method of sampling formations penetrated by a bit at the end of a drill stem in the process of rotary drilling, comprising lowering a core barrel through said drill stem to a position adjacent said bit, lowering said drill stem to latch said core barrel in said position, cutting a sample of said formation and displacing it into said .core barrel by reverse-circulation drilling,

raising said drill stem to release said core barrel containing said sample, and raising said core barrel containing said sample through said drill stem by reverse circulation of the drilling fluid.

10. In an apparatus for sampling the formations penetrated by a bit at the end of a rotary drill stem comprising a core bit attached to the lower end of said drill stem to cut a core, a core barrel, a latch for said core barrel at the lower end of said drill stem adjacent said bit, said latch being operable to hold said core barrel at the lower end. of said drill stem during reverse circulation drilling; and means for remotely actuating said latch to release said core barrel whereby said core barrel may be lowered through said drill stem and latched in position adjacent said bit by direct circulation during the process of reverse-circulation drilling, and said core barrel containing said sample may be raised hydraulically through said drill stem without materially interfering with drilling operations.

11. An apparatus for sampling formations penetrated by a bit at the end of a rotary drill stem comprising means to latch said core barrel in position adjacent said bit by rotation of said drill stem in a clockwise direction, means to out a sample of said formation and displace it into said core barrel, and means to release said latching means by rotating said drill stem in a counterclockwise direction whereby said formations may be sampled by reverse circulation drilling and said core barrel containing said sample may be raised to the surface through said drill stem by reverse circulation of the drilling fluid.

12. An apparatus for sampling formations penetrated by a bit at the end of a rotary drill stem comprising a core barrel, a latch adapted to hold said core barrel in position adjacent said bit, cam means adapted to actuate said latch by relative rotation between said drill stem and said bit, a fluid by-pass around said core barrel, a valve in said fluid passage operated by said relative rotation, said valve being adapted to open and said latch being adapted to close by rotation of said drill stem in a first direction, and said valve being adapted to close and said latch being adapted to unlatch when said drill stem is turned opposite to said first direction, whereby said core barrel is retained adjacent said bit during reverse-circulation drilling and is remotely released by rotation of said drill stem to permit said core barrel to be raised through said drill stem to the surface by piston action during reverse circulation of the drilling fluid.

13. An apparatus for sampling formations penetrated by a bit at the end of a drill stem comprising a core barrel, means adapted to latch said core barrel in position adjacent said bit when the weight of said drill stem is placed upon said bit, means to cut a sample of said formation and displace it into said core barrel, unlatching means adapted to release said core barrel from said position by removing the weight of said drill stem from said bit, whereby said core barrel may be lowered to and latched in said position, said sample may be cut by reversecirculation drilling, and raised to the surface through said drill stem by reverse circulation without materially interfering with drilling operations. I

14.. In an apparatus for sampling subterranean formations penetrated by a bit at the end of a drill stem comprising a core barrel, said core barrel defining a recess therein, a-mandrel connected to the lower end of said drill stem, a sleeve connected to said bit and slidably disposed about said mandrel, projections on said mandrel and on said sleeve adapted to permit limited relative longitudinal movement and to prevent relative rotation between said mandrel and said sleeve, spring catches associated with said mandrel, said catches being adapted to be displaced radially by said sleeve into said recess to hold said core barrel when said mandrel and said sleeve are in a compressed position, whereby said catches are released remotely by raising said drill stem to permit said core barrel to be raised through said drill stem by reverse circulation of said drilling fluid.

RALPH L. HENDRICKSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 473,910 Bullock May 3, 1892 2,068,762 Pennington Jan. 26, 1937 2,135,737 Stokes Nov. 8, 1938 2,277,989 Kinnear Mar. 31, 1942 

